U.S. Pat. No. 3,875,508, issued Apr. 1, 1975, entitled "Metering Electrical Energy (KWH) In Single Phase System"--Miran Milkovic, inventor--assigned to the General Electric Company, describes an electronic kilowatt hour meter which employs many of the principles used in the present invention and which operates to generate high frequency output pulses from the output of an analog-to-pulse rate converter comprising a part of the meter. The system described in this patent, however, does not include automatic error correction for automatically correcting system offset errors, which failing tends to limit the overall dynamic operating range of the metering system disclosed in this prior art patent.
U.S. Pat. No. 3,955,138, issued May 4, 1976, for an "Electric Energy Consumption Meter With Input Transformer Having Single Resistance Terminated Secondary Winding Coupled To C-MOS Switches Driven By Pulse Width Modulated Control Signals"--Miran Milkovic, inventor, and assigned to the General Electric Company, describes an electronic watt/kilowattt hour meter of the same general type as those discussed above, but which includes automatic error correction capability. The metering system described in pending U.S. patent application Ser. No. 330,660, filed Dec. 14, 1981, now U.S. Pat. No. 4,485,343, entitled "Electronic Watt and Watthour Meters With Analog and Digital Outputs And Having Automatic Error Correction", Miran Milkovic, inventor, and assigned to the General Electric Company, also describes a metering system which includes automatic error correction. The two metering systems described in U.S. Pat. No. 3,955,138 and in U.S. application Ser. No. 330,660 each are limited in their frequency of output pulses which they can derive for metering purposes, however, due to the effect of a superimposed 2.omega.t component in the multiplier output on the integrator ramp voltage of the analog-to-pulse rate converter, the output pulse rate of these circuits is limited. This characteristic consequently limits the time period required for the metering circuit to generate output metering pulses. In order to overcome these shortcomings of the prior art metering circuits, the present invention was devised.